I. Field
The present disclosure relates generally to communication, and more specifically to techniques for encoding and decoding data.
II. Background
A multiple-access communication system can support communication for multiple users by sharing the available system resources. The resources allocated to the users are dependent on the multiple-access scheme implemented by the system. For example, the system may allocate resources on the basis of time, frequency, code space, and/or transmit power. A user may establish a link with the system by sending an access request to the system and receiving an access grant with the allocated resources. The user may then communicate with the system via the established link.
A multiple-access system typically reserves some resources for transmission of signaling to the users. The signaling may be for various types of information needed for proper system operation, such as access grants. The signaling is often sent on a signaling channel, which may also be called an overhead channel, a control channel, or a broadcast channel.
A signaling channel is typically sent as either a unicast channel or a broadcast channel. For a unicast signaling channel, signaling messages for individual users are encoded separately and then sent on the signaling channel specifically to these users. Encoding each message separately results in poor coding efficiency. For a broadcast signaling channel, messages for all users are encoded together and then sent on the signaling channel to all users. Encoding all messages together improves coding efficiency. However, the broadcast signaling channel is typically operated in a manner such that all users, including the user with the worst channel conditions, can reliably decode this signaling channel. This may be achieved by using a low code rate and/or high transmit power for the broadcast signaling channel. Operating the broadcast signaling channel to satisfy the worst-case user often results in inefficient use of the resources allocated for the signaling channel.
There is therefore a need in the art for techniques to more efficiently transmit signaling messages in a multiple-access system.